Here is how I would do it: Take a starting point, and then randomly branch out from there to some random number of branches or distance, drawing lines (made out of quads) as you go. You can bias the expansion towards a point. To do this, create a 2D vector with random x and y coordinates, normalize it, and add the bias vector. If you render it to a FBO, you can also blur it to make it look brighter (bloom): http://www.gamerendering.com/2008/10...filter-shader/.